The same thing here. I confirm the bug exist as of 28-Sep-2018.
We have <10 non live data sources each extracting just ~20 rows from Tabular models my means of DAX. Extracts themselves happens in ~1 minutes in parallel, but union them into common dataset takes 12-15 minutes, while should be few seconds.
Do you know whether bug request was raised for this?
@Rookarumba, this happens when you refresh data at the point of time when combined data set is refreshed. Data extracts are quick, but not union operarion. Im not even saying about data transformations.
We have 8 gb RAM to union ～120-150 rows. Completely not applicable performance for application that cost that money.
What is the way suggested? If that it to publish pbx to pbi reporting service and do scheduled refresh, its not our case. SLA mins are 10 min.
I have a report that basically I load few tables from excel file and accessing Windows Insight Usage from our account (Details and Summary) and take hours (6 or more) when a single change is happening. Example change the location of excel file using a new version of values. The application can switch from MSAccess Database from Excel.... In this case is worst. Failed.
Something almost at the end using Excel fail and I have to start over.... Any help will be very appreciated.
This was happening with me, then I got a System.OutOfMemoryException... It finally opened after I opened the file in another instance of excel. The process was 4.5GB and yet the file I was trying to open is 8MB... MSFT I think your PowerQuery has some memory leaks.